Sorry to hear of the issue.
The council can be pushed - if need be you can involve the Local Government Ombudsman who can force the council to act.
As to where you stand, excessive noise can be classed as a "statutory nuisance" under the Environmental Protection Act 1990 - to count as a statutory nuisance the noise has to be either :
1. unreasonably and substantially interfere with the use or enjoyment of a home (which it does in your case); or
2. injure health or likely to injure health.
Given the facts in your question, I would therefore be confident in suggesting the noise you complain of is in fact a statutory nuisance - if you make a formal complaint to the council now. If they agree with you, they will serve an abatement notice on the business and the business then has to stop or restrict the noise to social hours.
If the council does not uphold the complaint, contact the Ombudsman here: https://www.lgo.org.uk
If the LGO sides with you, they will force the council to act - the council will then serve a notice on the business.
The owners of the business would be prosecuted if they disregarded the abatement notice - they can fine the owners and they can apply to the county court for an injunction (a court order to stop the light from being a problem) and if it gets to this stage it is serious for the owners as they face 2 years in prison for contempt of court if they still disregarded that court order.
The other option - consider a complaint to your local magistrates court under S.82 of the Environmental Protection Act 1990. You would need evidence of the noise (preferably in a diary to prove the extent of the noise). If approved then the court will issue a noise abatement order. Before applying to the court you would need to send a warning letter to the neighbour (see attached template) to give them 3 clear days to stop.
If they persist, you can apply to the local magistrates court – if you contact the clerk at the court and say that you want to make a noise complaint.
Finally, send a cease and desist letter to the business - threaten them with a civil injunction unless they stop.
A template “cease and desist” letter is available at this site : https://www.lawdepot.co.uk
If you go to the search box in the top right corner of the site, it will bring up a list - you want the "general" letter. You can use your own letter if you wish - it just has to make it clear this is a cease and desist letter, that you demand they stop their conduct, and that if they do not within 14 days you will apply to the court for the injunction and seek your costs.
That letter may well be enough to stop the conduct - as an injunction is a serious legal remedy.